Avoid storing empty third party settings on the content type configuration

Problem/Motivation

When a content type is configured to not be associated with any menu the empty options for that choice are saved in the node type config entity as third party settings and that creates fake dependency on menu_ui.

Steps to reproduce

- Create a new content type and uncheck all options for "menu settings".
- Inspect the configuration created and notice the following configuration

dependencies:
  module:
    - menu_ui
third_party_settings:
  menu_ui:
    available_menus: {  }
    parent: ''

Proposed resolution

Stop storing third party settings when the choices are empty.
Only apply the defaults (preselect the main menu) when the content type is created for the first time.

Remaining tasks

Code the solution

User interface changes

None

API changes

None

Data model changes

Node types will store less configuration when they are not associated with a menu

Release notes snippet

Content types that are not associated with any menu won't store third party settings anymore.